Control apparatus for controlling internal combustion engines

Abstract

In a control apparatus for controlling a variable valve actuation system employed in an internal combustion engine, engine / vehicle sensors are provided to detect at least a cylinder pressure in an engine cylinder for monitoring a change of state in combustion, arising from fluctuations in states / characteristics of air-fuel mixture such as a change in fuel property. Also provided is a control system that controls the variable valve actuation system responsively to a manipulated variable modified based on the cylinder pressure reflecting the change of state in combustion by a model of combustion.

Description

TECHNICAL FIELD [0001] The present invention relates to an internal combustion engine employing a variable valve actuation control (VVC) system for at least one of intake and exhaust valves, and specifically to the improvement of an engine control technology suited to internal combustion engines such as a four-stroke-cycle gasoline engine, a two-stroke-cycle gasoline engine, a four-stroke-cycle Diesel engine, a two-stroke-cycle Diesel engine, a premix compression ignition engine, and the like. BACKGROUND ART [0002] In recent years, a variable valve actuation control (VVC) system, capable of variably adjusting a valve lift and valve timing of at least one of intake and exhaust valves of an internal combustion engine depending on engine operating conditions, is widely utilized for controlling a charging efficiency, an effective compression ratio, and an amount of residual gas of the engine, thereby enhancing the combustion performance and engine power performance and exhaust emission ...

AI Technical Summary

Benefits of technology

[0017] It is, therefore, in view of the previously-described disadvantages of the prior art, an object of the invention to provide a control apparatus for controlling an internal combustion engine employing at least a VVC system, in which a change in the state of combustion is detected, effective compression ratio ε′ is adjusted by the VVC system responsively to the detected combustion state change, a deviation of the ignition lag from an optimal value, which deviation may arise from a change in air-fuel mixture temperature, a change in air-fuel mixture pressure, and changes of various states / characteristics of air-fuel mixture (e.g., a change in turbulence intensity, and a change in fuel property), is satisfactorily compensated for, and thus a deviation of the combustion characteristic value from its desired value can be minimized to optimally control combustion in real time.

Problems solved by technology

However, in the prior-art internal combustion engine employing the VVC system, a manipulated variable of the VVC system is not determined based on a detected combustion characteristic value of the internal combustion engine.

Therefore, it is impossible to correct or compensate for a deviation of the combustion characteristic value from a desired value (or an optimal value), which deviation may occur owing to a change in fuel property.

This leads to reduced engine power output and deteriorated emission control performance.

However, according to the system of JP1-315631, the effective compression ratio remains high during cranking, thus resulting in an undesirable drop in cranking speed.

Thus, it is difficult to minimize a deviation of the combustion characteristic value from a desired value.

Thus, it is difficult to minimize a deviation of the combustion characteristic value from a desired value.

However, even after cranking operation, the VVC-system manipulated variable, i.e., intake valve closure timing IVC remains retarded and set to a fixed value, regardless of the state of combustion, thus deteriorating the startability or self-ignitability during start operation.

As discussed above, it is difficult to minimize a deviation of the combustion characteristic value from a desired value.

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